CCS C Software and Maintenance Offers
FAQFAQ   FAQForum Help   FAQOfficial CCS Support   SearchSearch  RegisterRegister 

ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

CCS does not monitor this forum on a regular basis.

Please do not post bug reports on this forum. Send them to CCS Technical Support
Protocols for RS485

 
Post new topic   Reply to topic    CCS Forum Index -> General CCS C Discussion
View previous topic :: View next topic  
Author Message
Ian McCrum



Joined: 26 Oct 2003
Posts: 14
Location: Northern Ireland

View user's profile Send private message Visit poster's website

Protocols for RS485
PostPosted: Sun Nov 14, 2004 1:23 pm     Reply with quote
A ling time ago, I implemented several RS485 networks using a Master-Slave approach, slow baud rates, delays to allow line turnaround, resistors to bias the line to avoid false startbits when all drivers are tristate. These worked fine...

I typically use 4 wires and have a PC as the master, this allows use of hyperterminal for testing, I use pure ASCII and a "lline of text" at the heart of the protocol.

I am hoping to play with an embedded linux board talking to lots of "cable bulges" , the cable bulge will be PICs.

I wonder if there is information anywhere on actuak RS485 protocols in common use? presumably various fieldbuses are documented. If I recall correctly, the original Apple Macintosh network (localtalk?) used RS485.

Does anyone have any docs on actual RS485 LANs?
tia
Ian McCrum
_________________
Ian McCrum, email address held at
www.eej.ulst.ac.uk/~ian
Humberto



Joined: 08 Sep 2003
Posts: 1215
Location: Buenos Aires, La Reina del Plata

View user's profile Send private message

PostPosted: Sun Nov 14, 2004 6:54 pm     Reply with quote
Hi Ian,
Quote:

If I recall correctly, the original Apple Macintosh network (localtalk?) used RS485.



Yes but, localtalk reffers only to the phisical layer of the network.
Itīs pretty old but good enough to be used in almost any application, its very
robust in industrial enviroments.

Regarding the protocol they used, - wich is what you are asking -is Apple Talk
and you will find good info related this matter in:
[url]
http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/applet.htm#xtocid45
[/url]

HTH,

Humberto
Ian McCrum



Joined: 26 Oct 2003
Posts: 14
Location: Northern Ireland

View user's profile Send private message Visit poster's website

Thanks for appletalk links
PostPosted: Mon Nov 15, 2004 3:13 am     Reply with quote
Many thanks, the URL was just what I was looking for.

On reflection I need to find a LLC and MAC that suits RS485 and works with the network layers and above of TCP/IP ( which I know and love)

... a quick hack may well work but there must be a better way.

I'll study the appletalk data (and a datasheet on the Zilog 8230) to see if it makes sense. ( the linux end should not be a problem and apple did support 6502s running apple/local talk)

Very kindest regards
Ian
_________________
Ian McCrum, email address held at
www.eej.ulst.ac.uk/~ian
Display posts from previous:   
Post new topic   Reply to topic    CCS Forum Index -> General CCS C Discussion All times are GMT - 6 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group